Answer
$-\frac{\sqrt{23}}{8}$.
Work Step by Step
The given expression is
$=-\sqrt{\frac{23}{64}}$
Use quotient property of square roots.
$=-\frac{\sqrt{23}}{\sqrt{64}}$
Use $64=8^2$.
$=-\frac{\sqrt{23}}{\sqrt{8^2}}$
Simplify.
$=-\frac{\sqrt{23}}{8}$.
